#include<bits/stdc++.h>
using namespace std;

constexpr int mod=998244353,maxn=1010,maxm=12,maxs=1<<maxm;

int inv[maxn],a[maxm],b[maxm],pf[maxs],pg[maxs],pgi[maxs],c[maxn][maxn],sumab[maxs],sumb[maxs],pm[maxs],pmi[maxs],all[maxm];

int main()
{
	ios::sync_with_stdio(false),cin.tie(0);
	int n,m,i,j,s,x,ini=0;
	cin>>n>>m;
	inv[1]=1;
	for(i=2;i<=n;i++) inv[i]=(mod-mod/i)*1ull*inv[mod%i]%mod;
	c[0][0]=1;
	for(i=1;i<=n;i++)
	{
		c[i][0]=1;
		for(j=1;j<=i;j++)
		{
			c[i][j]=c[i-1][j]+c[i-1][j-1];
			if(c[i][j]>=mod) c[i][j]-=mod;
		}
	}
	for(i=0;i<m;i++) cin>>a[i];
	for(i=0;i<m;i++)
	{
		cin>>b[i];
		if(!b[i]) ini|=1<<i;
		all[i]=1;
		for(j=1;j<=b[i];j++) all[i]=all[i]*(a[i]-j+1ull)%mod;
	}
	for(s=1;s<(1<<m);s++)
	{
		int u=__builtin_ctz(s);
		sumab[s]=a[u]-b[u]+sumab[s^1<<u];
		sumb[s]=b[u]+sumb[s^1<<u];
	}
	for(s=ini;s<(1<<m);s=(s+1)|ini) pm[s]=pmi[s]=1;
	pg[ini]=1;
	pgi[ini]=inv[n-sumab[ini]];
	int sb=sumb[(1<<m)-1];
	for(i=1;i<=sb;i++)
	{
		for(s=ini;s<(1<<m);s=(s+1)|ini)
		{
			pm[s]=pm[s]*(n-i+1ull-sumab[s])%mod;
			pmi[s]=pmi[s]*1ull*inv[n-i+1-sumab[s]]%mod;
		}
		for(s=(1<<m)-1;s>=0;s--)
		{
			if((s&ini)!=ini||sumb[s]>i) continue;
			int f=0,g=0;
			for(x=0;x<m;x++)
			{
				if(!(s>>x&1)||!b[x]) continue;
				int p=s^1<<x,mul=1ull*all[x]*c[i-1-sumb[p]][b[x]-1]%mod*pmi[p]%mod;
				f=(f+(1ull*pgi[p]*sumab[p]+pf[p])%mod*mul)%mod;
				g=(g+1ull*mul*pg[p])%mod;
			}
			if(i==sb)
			{
				cout<<(f+sb)%mod<<'\n';
				return 0;
			}
			pf[s]=(pf[s]+1ull*f*pm[s])%mod;
			pg[s]=(pg[s]+1ull*g*pm[s])%mod;
			pgi[s]=(pgi[s]+1ull*pg[s]*inv[n-i-sumab[s]])%mod;
		}
	}
	cout<<0<<'\n';
	return 0;
}